Place the sliced quince in a bowl of cold water to prevent discoloring while you prepare the sugar/honey syrup. Combine the water, sugar, honey, lemon juice, vanilla bean and cardamom in a heavy bottomed 3 qt. pot. Bring to a boil then add the sliced quince. Reduce the heat to low, cover the quince with a circle of parchment paper (to prevent them from drying out) and simmer on low heat for about 50-60 minutes. Test them with a paring knife; they should be tender. Let them cool completely in the syrup. They can be refrigerated for up to a week in the syrup. The longer they sit, the rosier the color. To prepare the tart, strain the fruit from the syrup (save the syrup for cocktails!) and slice thinly. Place the quince slices on a baking sheet lined with two or three paper towels to remove excess syrup.

In the bowl of a food processor fitted with the blade attachment, combine the flour, cocoa, cardamom, salt and confectioners’ sugar; pulse a few times to combine. Add the cold butter and pulse until you have coarse crumbs. Add the egg yolk, pulsing just to combine, then add the tablespoon of water, pulsing a few times to incorporate. Turn the dough out onto a sheet of plastic wrap, dough together, shape into a disc and wrap in plastic wrap. Refrigerate for half an hour before rolling out on a lightly floured sheet of parchment paper. Roll into a circle about 11” in diameter and ⅛” thick. Fit into a lightly greased tart pan, pressing the dough into the bottom and up the sides of the tart pan. Refrigerate the tart shell for half an hour before partially blind baking.

Preheat the oven to 375 degrees F. Line the tart shell with a sheet of parchment paper or aluminum foil that extends over the sides. Tuck the paper (or foil) into the pan and over the sides, making sure it fits snugly. Fill with pie weights or dried beans. Place on a baking pan and bake for 15 minutes. Wearing oven mitts, carefully remove the baking pan from the oven and remove the parchment paper (or foil) and pie weights (or beans). Reduce the oven temperature to 350 degrees F. Use a fork to prick the bottom of the tart shell and return the tart to the oven for an additional 10 minutes, just until the dough is no longer raw on the bottom. Place the baking sheet with the tart shell on a cooling rack to cool completely while you prepare the filling.

In the bowl of a standing mixer fitted with a paddle attachment, combine the butter and sugar. Add the egg and mix to combine then stir in the walnuts, flour, salt and vanilla. Mix just until incorporated.

To assemble the tart:

Preheat the oven to 375 degrees F. Place the cooled, partially baked tart shell on a baking sheet. Spread the frangipane over the tart shell and bake the tart (without the fruit at this point) for 12 minutes, just to set the filling. Remove the baking sheet from the oven. Let the tart cool for a few minutes, then starting from the outer edge, place the slices of poached quince around the tart, overlapping them slightly, gently pressing them into the filling. Continue until the tart is filled. Bake at 375 degrees F for about 30 minutes, until the tart is slightly puffed, the filling is set and the fruit is tender. Place on a rack to cool before slicing.